A series of tweets by University of Maryland police indicated the guard was shot early Tuesday near the University College’s Inn and Conference Center in what appears to be a commercial armed robbery, and that guard was taken to a hospital. He is in critical condition.

Police added that one person was taken into custody and they were looking for a second.

The all clear was given shortly after 7 a.m.

According to its website, the university college offers online courses and enrolls about 80,000 students around the world, including active duty military personnel. Its headquarters and conference center in the Washington, D.C., suburbs are next to the University of Maryland, College Park campus.